Production of high octane motor fuels



Nov. 1, 1960 c. N. KIMBERLIN, JR., ET AL 2,958,644

PRODUCTION OF HIGH OCTANE MOTOR FUELS 4 Sheets-Sheet 1 Filed May 1, 19571 u zocfi wio Tmmnwl 20:55:09 -39: on r I IIIIIHIIIH I H II M 5N Ivmohqm nmm 8 RE vm $51 uEEmEomE: 2:9 IAHIIIIJ 0: ON k EmEEE wfiw fii a .t1- Q3850: amobmqmmmo =1 mm 1 3 l MW @E mfimg r F NN 12 a w: 6% 503% wCharles Newton Kimberlin, Jr. I William Judson Maffox "venfors yAttorney Nov. 1, 1960 c. N. KIMBERLIN, JR., ET AL 2,958,644

PRODUCTION OF HIGH OCTANE MOTOR FUELS Filed May 1, 1957 4 Sheets-Sheet 2PLATINUM REFORMING OF LIGHT NAPHTHA PLUS MOLECULAR SIEVETREAT-N-PARAFFINS REMOVED OCTANE NUMBER OF REFORMATE x FEED O PLATINUMHYDROFORMATE VOL. 9,,

- PARAFFINS REMOVED I5 7o E a5 RESEARCH O. N. OF FEED TO SIEVE TREATCharles Newton Kimberlin, Jr. William Judson Maffox By Attorney Nov. 1,1960 PRODUCTION OF Filed May 1, 1957 C. N. KIMBERLIN, JR., ET AL HIGHOC'I'ANE MOTOR FUELS 4 Sheets-Sheet 3 FIGURE '3 REFORMING LIGHT VIRGINNAPHTHA YIELDOCTANE NUMBER RELATIONSHIPS FOR I T A e 84 s 5vE RE TINHYDROFORMING PLUS MOLECULAR SIEVE TREA WITH HYDROISOMERIZATION 0F N-PARAFFINS Q 33 HYDROFORMING LL I HYDROFORMING PLUS MOLECULAR SIEVETREAT- 2 WITH N-PARAFFIN AROMATIZATION :E 9 as -l 2 HYDROFORMING PLUS OMOLECULAR SIEVE TREAT- N N'PARAFFIN DISCARD 4 e4 g E g m 4.

In D a0 a5 I05 OCTANE NUMBER OF C 'I-GASOLINE Charles Newton Kimberlin,Jr.

WiII

iom Jud Mam) Inventors By Attorney Nov. 1, 1960 c. N. KIMBERLIN, JR.,ETAL 8,

PRODUCTION OF HIGH OCTANE MOTOR FUELS Filed May 1, 1957 4 Sheets-Sheet 4FIGURE- 4 PLATINUM REFORMING OF LIGHT NAPHTHA PLUS MOLECULAR SIEVE TREATOCTANE NUMBER OF TREATED MATERIAL VS. OCTANE NUMBER OF REFORMATE X FEEDl l Q-PLATINUM HYDROFORMATE I I 95 RESEARCH o. N.

OF MOLECULAR SIEVE TREATED ,0

PRODUCT 9o e5 8O 9o RESEARCH O. N. OF FEED TO MOLECULAR SIEVE TREATCharles Newton Kimberlin, Jr. William Judson Maffox By Attorneylnvenfors United States Patent PRODUCTION OF HIGH OCTANE MOTOR FUELSCharles Newton Kimberlin, Jr., and William Judson Mattox, Baton Rouge,La., assignors to Esso Research and Engineering Company, a corporationof Delaware Filed May 1, 1957, Ser. No. 656,742

14 Claims. (Cl. 208-64) The present invention relates to the reformingof hydrocarbons and particularly to an improved method for hydroformingof naphtha fractions to produce 100+ octane number motor fuels.

Hydroforming is a well known and widely used process for upgradinghydrocarbon fractions boiling in the motor gasoline or naphtha boilingrange to increase their octane numbers and to improve their burning orengine cleanliness characteristics. In hydroforming, the hydrocarbonfraction or naphtha is contacted at elevated temperatures and pressuresand in the :presence of hydrogen or hydrogen-rich process gas with solidcatalytic materials under conditions such that there is no netconsumption of hydrogen and ordinarily there is a net production ofhydrogen in the process. A variety of reactions occur duringhydroforming including dehydrogenation of naphthenes to thecorresponding aromatics, hydrocracking of paraffins, isomerization ofstraight chain paraffins to form branch chain parafiins,dehydrocyclization of paraflins and isomerization of compounds such asethylcyclopentane to form methylcyclohexane which is readily convertedto toluene. In addition to these reactions, some hy drogenation ofolefins and polyolefins occurs if such compounds are present and sulfuror sulfur compounds are eliminated by conversion to metal sulfidesand/or hydrogen sulfide making the hydroformate burn cleaner or formless deposits when used as the fuel in an internal combustion engine.

Hydroforming is usually applied to a rather wide boiling range naphtha,i.e. to one having a boiling range of from about 125 F. to about 400430F. It has been known that the lower boiling naphthas are notsubstantially improved by hydroforming processes as ordinarilyconducted. The extensive report entitled An Appraisal of CatalyticReforming in Petroleum Processing for August 1955, for example, stateson page 1l740ptimum reformer utilization is obtained by not using feedstock constituents boiling much below 200 F .which do not contributegreatly to increased octane during reforming as these merely take upreformer capacity better used for high boiling materials moresusceptible to octane upgrading. In view of the continuing demand formore and higher octane number gasolines, however, it is becomingincreasingly important to upgrade naphthas to even higher octane levelsand in this connection it is becoming essential to improve the octanenumber of these lower boiling fractions.

It is the object of this invention to provide the art with an improvedmethod for reforming or upgrading naphthas.

It is also the object of this invention to provide a simple andeffective method for hydroforming petroleum naphthas boiling in therange of from about l-400 F preferably from about l50-350 F.

It is a further object of this invention to provide the art with arelatively simple, effective method for converting light petroleumnaphthas having end points of 225 to 250 F. into 100+ octane numberproducts in high yields.

These and other objects will appear more clearly from the detailedspecification and claims which follow.

It has now been found that naphtha fractions can be advantageouslyupgraded to 100+ octane number products by hydroforming the same incontact with hydroforming catalysts of the molybdenum oxide type as wellas of the platinum metal type at temperatures of about 850-975 F.,preferably 875 950 F., and at pressures up to about 400 p.s.i.g. and atfeed rates sufiiciently high that the hydroformate has an octane numberof about to about and thereafter contacting the hydroformate withmolecular sieves or synthetic alumino-silicate zeolites whichselectively remove the normal paraflins from the hydroformate.

In a preferred embodiment, light petroleum naphtha fractions areconverted into very high octane number light naphtha products with anunexpectedly high yield advantage by hydroforming them in contact withplatinum-containing catalysts at pressures below p.s.i.g. and preferablyat pressures of from 50 to 100 p.s.i.g. to an intermediate octane numberlevel of about 90 and thereafter treating the hydroformate withmolecular sieves of the proper type to remove n-paraflins. By thisparticular combination of process steps it is possible (to obtain alight naphtha hydroformate having an octane number of 100 or more withat least about a 5 vol. percent yield advantage, even withoututilization of the separated n-paraffins, over hydroforming the samefeed stock to the same octane number directly. In addition, by thecombination process of this invention it is possible to increase thefeed rates to a hydroforming unit, in some cases as much as three orfourfold increase over that necessary to produce hydroformates having anoctane number of 100 or higher.

It has, of course, been known for some time that certain zeolites, bothnaturally occurring and synthetic, sometimes termed molecular sieves,have the property of separating straight chain from branched chainhydrocarbon isomers, as well as from cyclic and aromatic compounds.These zeolites have innumerable pores of uniform size and only moleculessmall enough to enter the pores can be adsorbed. The pores may vary indiameter from 3 or 4 Angstroms to 15 or more, but it is a property ofthese zeolites or molecular sieves that any particular product has poresof substantially uniform size.

The scientific and patent literature contains numerous references to thesorbing action of natural and synthetic zeolites. Among the naturalzeolites having this sieving property may be mentioned chabazites. Asynthetic zeolite with molecular sieve properties is described in US.Pat. 2,442,191. Zeolites vary somewhat in composition but generallycontain the elements silicon, aluminum and oxygen as well as an alkalimetal and/ or an alkaline earth metal element, e.g. sodium and/orcalcium. The naturally occurring zeolite analcite, for instance, has theempirical formula NaAISi O -H O. Barrer (U.S. 2,306,610) teaches thatall or part of the sodium is replaceable by calcium to yield, ondehydration, a molecular sieve having the formula (Ca, Na Al Si O Black(U.S. Pat. 2,522,426) describes a synthetic molecular sieve zeolitehaving the formula 4CaO-Al O -4SiO A large number of other naturallyoccurring zeolites having molecular sieve activity, i.e. the ability toadsorb a straight chain hydrocarbon and exclude or reject the branchchain isomers and aromatics because of differences in molecular size,are described in an article entitled Molecular Sieve Action of Solids,appearing in Quarterly Reviews, vol. III, pages 293-320 (1949),published by the Chemical Society (London).

Although it has, in the past, been proposed to effect the separation ofstraight chain hydrocarbons from isoparafiins and aromatics it has beenfound that a very total light naphtha feed is obtained at 100.8 research.octane number. If, on the other hand, the total llght naphtha feed ishydroformed to 100.8 research octane number, a yield of about 58 vol.percent on total naphtha feed is obtained. Furthermore, if the totallight naphtha feed is hydroformed to about 80 research octane number andthe hydroformate treated with 5 A. molecular sieves, a treated productof 91 research octane number is obtained in yields of about 68 vol.percent whereas the total light virgin naphtha feed can be hydroformedto 91 research octane number with yields of about 75 vol percent basedon the total naphtha feed. However, by hydrofor-ming the total lightnaphtha feed to about 93 research octane number and treating thehydroformate with 5 A. molecular sieves, a treated product of 100.8research octane number is obtained in yields of about 6364 vol. percentwhereas, as noted above, hydroforming of the total light virgin naphthafeed to 100.8 research octane number would give a yield of only about 58vol. percent based on the total light naphtha feed.

Similar results are obtainable with heavy naphtha hydroformates. Whileit is necessary to go to somewhat higher levels in the case of heavynaphthas, there is a very definite yield advantage when forming 103105and higher octane products. The octane level race has already reachedthe point where there is a definite need for improved hydro-formingprocesses for producing 105 ON heavy naphtha hydroformates.

The combination process of the present invention offers further,important process advantages in that it permits substantially longerprocess cycles in fixed bed operations and permits longer catalystresidence times in the reactor in fluid hydroforming operations. Forexample, if a 225 F. end point naphtha is hydroformed to 100.8 researchoctane number in a 50 p.s.i.g. fixed bed platinum hydroformingoperation, the run would have to be terminated after about 1 hour andthe catalyst regenerated and reactivated. If, on the other hand, thatnaphtha is hydroformed to only 93 research octane number the run may becontinued for about 8 hours before regeneration and reactivation of thecatalyst becomes necessary. Since the number of regenerations that acharge of catalyst can undergo before it becomes deactivated to a pointWhere it is necessary to replace it with a fresh charge of catalyst islimited, it is obvious that the process of the present invention offersthe further advantage of giving long catalyst life.

Reference is made to the accompanying drawings in which Fig. 1 is adiagrammatic flow plan of the process in accordance with the presentinvention and Figures 2, 3 and 4 show graphically several correlationsthat are illustrative of the results obtained by the process of thisinvention.

Referring to Fig. 1, naphtha feed is supplied through inlet line 10 tohydroformer 11 where it is contacted, in admixture with hydrogen-richrecycle gas supplied through line 12, with a hydroforming catalyst underconditions of temperature, pressure and the like as described below.While hydroformer 11 is shown as a single vessel it will be understoodthat this may comprise several reactor vessels in series with reheatingmeans between each. The hydroformer may be a fixed or moving bed reactoror the reactor system may utilize the fluidized solids technique.

Hydroformate is taken overhead from hydroformer 11 through line 13,cooled or condensed and passed to gasliquid separator 14. Hydrogen-richrecycle gas is removed from separator 14 via line 15 and returned to thehydroformer via inlet line 12. Excess gas is discharged from the reactorsystem through vent line 16.

fit

Hydroformate is withdrawn from separator 14 through line 17, heated tovaporization temperatures and charged to vessel 20 where the vapors arecontacted with suitable molecular sieve materials having an average porediameter of 5 Angstrom units. A suitable 5 A. molecular sieve may beprepared as follows: A solution of 600 g. of granular sodiummetasilicate (composition 29.1 wt. percent Na O, 28.7 wt. percent SiO42.2 wt. percent H O) in one liter of water is placed in a burette. Asecond solution of 370 g. of sodium aluminate in 538 ml. of water isplaced in a second burette. The two solutions are added dropwise withvigorous stirring over a period of two hours to 510 ml. water containinga little NaOI-I to give an alkaline solution at a temperature of 190 F.A slight excess of the metasilicate solution over the aluminate solutionis maintained during the addition. At the end of the addition, heat isremoved and stirring is continued for 10 minutes. The mixture isfiltered and washed. The precipitate, sodium alumino silicate is 4 A.sieve.

To prepare the 5 A. sieve, 35 g. of the wet filter cake is stirred atroom temperature for 1 hour in 600 g. of a 20% calcium chloridesolution. The mixture is filtered, washed and then dried at C. The driedproduct is calcined at 850 F. for 4 hours. The adsorbent or molecularsieve material is arranged in any desired manner in the adsorption toweror vessel 20. It may, for example, be arranged on trays or packedtherein with or without supports. Conditions maintained for themolecular sieve treatment inthe adsorption zone or vessel 20 are flowrates of 0.1 to 5 v./v./hr., pressures from atmospheric to severalhundred p.s.i.g., and temperatures sufficiently high to maintain thehydroformate in vaporous form i.e. -325 F. for light naphtha and up to400 or 425 F. for heavy naphtha.

Hydroformate substantially free from straight chain paralfins iswithdrawn from the adsorption zone or tower 20 via line 21, cooled orcondensed and passed to gasliquid separator 22 to separate a stabilizedliquid product which is withdrawn via line 23 and passed to productstorage or blending. Gaseous materials, including normally gaseousolefins used for regenerating the molecular sieves are withdrawn fromseparator 22 through line 24 for recycling to the molecular sievetreatment vessel.

When the molecular sieve material in vessel 20 becomes saturated withnormal paraffins, the flow of hydroformate is stopped and desorption orregenertaion of the sieves is begun. Desorption is preferably effectedby passing an olefin-containing gas such as propylene or a crackedrefinery gas rich in propylene or butylene preheated to about 200-250 F.through inlet line 25 into vessel 20. Thus without substantiallychanging the temperature of the adsorption zone or vessel 20, thestripping or desorbing gas replaces the adsorbed paraffins withpropylene and/or other olefins. The desorbed normal parafiins and thenon-olefinic constituents of the stripping gas are withdrawn from vessel20 via line 26, cooled or condensed and passed into gas-liquid separator27. Gases are withdrawn from separator 27 through line 28. Desorptioncan also be effected by passing hydrogen or natural gas through the bedor by raising the temperature or lowering the pressure in the bed, or bya combination of two or more of the foregoing expedients.

The desorbed normal paraffins are withdrawn from separator 27 via line29 and may be discharged through line 30 to n-paraffin product storagefor use as solvents or jet fuel or the like. If desired, however, then-paraffins may be passed from line 29 through line 31 to anisomerization or aromatization reactor 32 or through line 35 intohydroformer reaction zone 11 for retreatmentunder hydroformingconditions. Isomerization of the light normal parafiins is preferablycarried out as a hydroisomerization treatment or by means of a Friedel-Crafts catalyst such as aluminum chloride in which case a substantialpartial pressure of hydrogen will advantag egpsit ly be employed topromote selectivity and prolong catalyst life. Although a number ofcatalytic materials may be employed to promote hydroisomerization,nickel deposited upon silica-alumina or platinum on alumina orsilicaalumina are particularly useful for this purpose. For example, 5wt. percent nickel on silica-alumina may be employed at pressures ofabout 350 p.s.i.g. and at temperatures of about 700 F. to isomerize awide range of normal parafiins falling within the gasoline range.Hydrogen partial pressure in the hydroisomerization reaction zone may beprovided by withdrawing hydrogen-rich recycle gas from line 12 throughline 33. Ordinarily it is preferred to pass the hydrogen through asuitable guard bed or purifying zone to remove sulfur or hydrogensulfide therefrom which would have an adverse effect upon theisomerization catalyst. The isomerization products are removed fromreactor 32 through line 34 and passed into line 13 for cooling andrecovery of the non-normal parafiin constituents along with thehydroformate. Alternatively the normal parafiins may be treated incontact with an aromatization catalyst such as chromia-alumina,chromia-titania or M on zinc aluminate spinel at temperatures of from850-1050 F. and at pressures from atmospheric to about 150 p.s.i.g.

The virgin naphthas that may be treated in accordance with the presentinvention may be a wide cut boiling in the range of from about 110-375F., or it may be a narrow cut such as 1l0250 F. or preferably 150200 F.light naphtha or a heavy naphtha cut boiling in the range of from about200 to about 350 F. The C fraction, boiling below about 150 F., is notupgraded by the process to as great an extent as the C and Chydrocarbons and therefore the C fraction is not a particularlydesirable component of the feed. On the other hand, the presence of C inthe feed is not particularly harmful so that it may be preferred toinclude this fraction in the feed if doing so will avoid an additionaldistillation step in the feed preparation. The fraction boiling above200 F. up to 225 F. or 250 F. responds fairly well to the conventionalhydroforming processes employing either molybdenum oxide or platinumcatalyst at about 200 p.s.i.g. or higher and may be included in the feedto such processes. On the other hand, this fraction also responds wellto the present low pressure platinum process so that the method ofhandling this particular fraction of the virgin naphtha feed will dependupon circumstances such as availability of equipment and the volumes ofthe different boiling range fractions which it is desired to process.

In general it is preferred to process a wide boiling range naphtha orsay a 200 to 350 F. cut under essentially conventional conditions, i.e.with a conventional hydroforming catalyst such as 10% M00 upon activatedalumina or silica stabilized activated alumina at 100400, preferablyabout 200 p.s.i.g. and at temperatures of 850-975 F. or with a catalystconsisting essentially of about 0.6 wt. percent platinum upon highlypure alumina, for example, eta alumina prepared by hydrolysis ofaluminum amylate, aging to convert the hydrolyzate to beta aluminatrihydrate, drying and calcining. Pressures and temperatures forhydroforming with this platinum catalyst are essentially the same as forhydroforming with the molybdenum oxide catalyst.

It has been found that in the pressure range of from about atmosphericpressure to 125 p.s.i.g. it is possible with platinum-containingcatalysts to upgrade a light virgin naphtha having a mid-boiling pointof 169 F. and a research octane number of 66 into a hydroformate havinga research clear octane number of around 90 and higher in yields ofabout 75 vol. percent and into a hydroformate having a research clearoctane number of around 95 or higher in yields of about 68 vol. percent.In contrast thereto, hydroforming of this naphtha at 200 p.s.i.g. with amolybdenum oxide catalyst produces a hydroformate of only about 81research octane number in yields of about 75 vol. percent or about 85research octane number in yields of about 68 vol. percent. In furthercontrast thereto, hydroforming of this light naphtha at 200 p.s.i.g.with platinum-containing catalysts produces a hydroformate of onlyresearch octane number at 75 vol. percent yield. Moreover, it was foundimpossible to increase the research octane number much above about 85 byhydroforming this light naphtha with platinum-containing catalysts at200 p.s.1.g.

Under these reaction conditions thereis a tendency for carbon to form onthe catalyst and it therefore becomes necessary to regenerate thecatalyst by burning the carbonaceous deposits from the catalyst.Regeneration of platinum-containing catalysts is preferably effectedwith diluted air to facilitate control of the temperature ofregeneration and it is preferred to contact the regenerated orcarbon-free catalyst with undiluted air or oxygen-enriched gas attemperatures of 850- 1100" F. for from about 1 hour to 4 hours. Thehydroforming reaction may be carried out in fixed bed, moving bed, orfluidized solids type operations, the latter being preferred whenreaction conditions are such that frequent regenerations are necessaryand particularly when M00 catalysts are used.

It is also desirable to provide means for subjecting the regeneratedplatinum-containing catalyst or a portion of it in continuous operationto reactivation with a halogen or halogen compound such as chlorine orhydrogen chloride. A free halogen such as chlorine is the preferredtreating agent for reactivation. Aside from the accumulation of poisons,the deactivation of platinum hydroforming catalysts proceeds by twomechanisms, viz., (l) the loss of chlorine or other halogen that isnormally present as part of the catalyst composition and thatcontributes substantially to the catalyst activity and (2) theagglomeration of the platinum metal into relatively large or massivecrystals having diameters in excess of about 50 Angstrom units.Treatment of the catalyst with a halogen compound such as hydrogenchloride or the like is effective in restoring the halogen content ofthe catalyst to the desired level and to this extent is effective inrestoring the activity of deactivated or partially deactivatedcatalysts. On the other hand, treatment of the catalyst with anelementary halogen such as chlorine or the like, not only restores thecatalyst halogen content to the desired level but also accomplishes theredispersion of the platinum metal by breaking up the large platinumcrystallites. This treatment, therefore, is entirely eifective inrestoring the activity to deactivated catalysts whose activity loss wasnot due to the accumulation of poisons such as arsenic or the like.

Platinum-containing catalysts that may be used for hydroforming thenaphthas in accordance with the present invention are those containing0.01 to 1.0 wt. percent platinum or 0.1 to 2.0 wt. percent palladiumdispersed upon a highly pure alumina support such as is obtained fromaluminum alcoholate as per US. Patent 2,636,865 or from an aluminahydrosol prepared by hydrolyzing aluminum metal with dilute acetic acidin the presence of very small, catalytic amounts of mercury. A suitablecatalyst comprises about 0.1 to 0.6 wt. percent platinum widelydispersed upon alumina in the eta phase derived from aluminum amylateand having a surface area of about -220 sq. meters per gram. A preferredcatalyst for fluidized solids operations is one comprising a mixture ofa platinum catalyst concentrate consisting essential-ly of 0.3 to 2.0Wt. percent platinum on alumina rnicrospheres formed by spray drying analcoholate alumina hydrosol prepared in accordance with US Patent2,656,321 and mixed with suflicient unplatinized alumina to form acatalyst composition containing about 0.01 to 0.2 wt. percent platinum.A suitable molybdenum oxide-containing catalyst is one containing 5 to15 wt. percent preferably about 10 wt. percent M00 dispersed Thepressure in the reaction zone should be in the range of to 400 p.s.i.g.and is preferably about 50 p.s.i.g., in

the case of light naphtha hydroforming with platinum catalysts, 200p.s.i.g. for M00 catalysts and about 300 p.s.i.g. for platinum catalystswhen hydroforming a higher boiling feed such as the 200-350 F. virginnaphtha cut. The temperature of the catalyst bed should be in the rangeof from 800 to 975 F. In view of the fact that under the conditions oflow pressure and low recycle gas rates applied in accordance with thisinvention the dehydrogenation activity of the platinum metal catalystsis extremely high, the reaction temperatures may be somewhat lower thanused previously. The preferred temperature range is from 875950 F.

The naphtha feed is preheated to temperatures in the range of from900-1050 R, preferably about 975 F. to 1000 F. preparatory to chargingto the hydroforming reaction zone. recycle gas is preheated to 900 to1300 P., preferably about 1200 F. preparatory to charging to thehydroforming reaction zone. If desired, the naphtha and hydrogenrich gasmay be heated together in which event the preferred preheatedtemperature is in the range of from 900-1000 F.

The hydrogen-rich or recycle gas normally contains about 6590 mol.percent hydrogen with the remainder being light hydrocarbon gases. Theexact composition of the recycle gas depends upon the hydroformingreaction conditions and upon the pressure "and temperature at which therecycle gas is separated from the hydroforrnate. The amount of recyclegas employed may vary from 500 to 5000 and is preferably about 1000 to3000 standard cubic feet per barrel of naphtha feed.

In addition to preheating the naphtha feed and recycle gas, theadditional heat load may be supplied to the hydroforrning reaction zoneby the sensible heat of the regenerated catalyst in fluidized solidsoperations or by circulating reactor catalyst through a heating zone orby arranging heating coils in the catalyst bed or jacketing the reactorand circulating hot flue gases, mercury vapor, Dowtherm or the liketherethrough.

The hydroformate and process gases are removed from the reaction zone,passed through suitable catalyst recovery equipment, if desired ornecessary, and then passed through suitable heat exchanger and condenserequipment and thence into a gas-liquid separator. The gaseous productsare removed from the separator and any excess gas is rejected from thesystem. The recycle gas may, if desired, be scrubbed to remove hydrogensulfide and passed through a drier if excessive amount of water appeartherein.

Regeneration of the catalyst is effected as required by burningcarbonaceous materials therefrom with oxygencontaining gas attemperatures of 9001200 F., preferably at 1000-1100 F. The pressure inthe regeneration may be the same as during hydroforming or it may, ifdesired, be lowered to near atmospheric pressure. In burning off thecarbonaceous deposits a certain amount of water is formed by combustionof hydrogen in said deposits. This water is stripped from the catalystand passes overhead with the flue gases and is removed from the system.Excess air is used for the regeneration to insure the complete removalof carbon or coke from the catalyst prior to reactivation with chlorine.The regenerated or carbon-free platinum catalyst can advantageously betreated with air at temperatures of 850- 1100 F. for from 1 to 4 hours.The regenerated catalyst is then contacted with chlorine gas or amixture of chlorine gas and air in order to reactivate the catalyst,restore its chlorine content, and redisperse or break up the largeplatinum crystallites that form during use of the catalyst.

Th hl ri r al e su m be in h range of Hydrogen or hydrogen-rich processor 8 from 0.001 to 2 atmospheres, preferably 0.01 to 1 atmosphere. Thequantity of chlorine supplied may be in the range of 0.1 to 2.0 wt.percent preferably about 0.5 wt. percent based on the catalyst. Thechlorine treatment may be carried out for periods ,of from about 15seconds to 1 hour, preferably about 1 to 15 minutes. While the chlorinetreated catalyst may be subjected to air stripping to remove excesschlorine it is usually preferred to avoid stripping chlorine from thereactivated catalyst since the chlorine content governs thehydrocracking activity of the catalyst which in turn controls thevolatility of the hydroformate. The amount of chlorine which it isdesirable to have remaining on the stripped catalyst is related to theplatinum content of the catalyst. With high platinum content catalysts,a relatively high chlorine content is desirable and a correspondinglylower chlorine content is desirable for lower platinum contents. Ingeneral, the total amount of chlorine (i.e. both chemically combined andadsorbed) remaining on the catalyst when employing a catalyst of 0.6%platinum content may be in the range of about 0.2 to 1.25 wt. percentand is preferably about 0.5 to 1.0 wt. percent.

The hydroformate is withdrawn from the gas-liquid separator and isfurther treated with molecular sieves in accordance with the presentinvention. Essentially, the molecular sieve treatment is effected byvaporizing the hydroformate and passing the vapors through one or morezones or chambers charged with suitable molecular sieve materials. Inorder to separate the normal paraffins from the isoparafiins andaromatics in the hydroformate, the vapors should be treated withmolecular sieves having a pore size of approximately 5 Angstrom units,which will readily adsorb the normal parafiins contained in thehydroformate but will not adsorb the isoparafiins or aromatics. Ifdesired, the hydroformate can be passed through a guard-bed consistingof molecular sieve material having a pore diameter of 4 Angstrom unitsor smaller which will serve to remove any water or hydrogen sulfide orthe like. This is highly desirable since both water and certain sulfurcompounds are more strongly adsorbed than most hydrocarbons and it isdifficult to desorb them. Since these contaminants frequently occur inhydroformates in small amounts, continued use of the S A. sieves wouldrequire periodic interruptions to desorb the contaminants and restoreadsorbent capacity. By using a guard-bed of molecular sieve of 4 A. orsmaller pore diameter the contaminants are removed but the hydrocarbonsare not adsorbed. Since the capacity of the 4 A. and smaller sieves forwater is high, the total volume or amount of the 4 A. and smallermolecular sieves as compared to the total volume or amount of the 5 A.molecular sieves, is small. Ordinarily it is preferred to arrange theadsorbent units in pairs so that one unit may undergo desorption orregeneration while the other unit is on stream. Water may be desorbcdfrom the guard bed by passing hot gases such as dry air therethrough. Itshould be understood, however, that if the hydroforrnate is dry and/orsubstantially free of sulfur compounds it is not necessary to provide aguard bed.

The hydroformate is passed, preferably in vapor phase at temperatures ofabout 200 to 400 F., into the adsorption zone or towers. The adsorbent,any natural or synthetic zeolite of the molecular sieve type heretoforedescribed having a pore diameter of about 5 A., is arranged in anydesired manner in the adsorption zone or tower. It may, for example, bearranged ontrays or packed therein with or without supports. Conditionsmaintained in the molecular sieve treatment in the adsorption zone ortower are flow rates of 0.1 to 5 v./v. hr. temperatures of about 425 F.and pressures of from atmospheric pressure to several hundred pounds persquare inch.

Hydroformate substantially free from straight chain paraflins iswithdrawn from the adsorption zone or tower and is cooled or condensedand sent to storage orused through the exhausted bed of molecularsieves.

.for processing periods of 16 hours.

same octane number.

number motor fuel.

When the molecular sieves in the adsorption zone or tower becomessaturated with normal paraflins, as may be determined by conventionalmeans such as refractive index, gravity or spectrographic analysis ofthe efliuent, the flow of hydroformate is stopped and the desorptioncycle or regeneration of the sieves is begun. Desorption, as describedabove, may be effected by passing an olefincontaining gas, preferablyone containing a substantial proportion of propylene and preheated to200-2 50 F., The stripping gas may be passed through a guard-bedsimilarly to the hydroformate if necessary to remove contaminants thatmight become adsorbed upon the molecular sieve. Cracked refinery gasescontaining a major proportion of ethane and propane may also be used forstripping the adsorbed normal paraffins from the sieves. Withoutchanging the temperature of the adsorption zone or tower, the strippingor desorbing gas replaces the adsorbed paraflins with the olefins orpropylene. The

'desOIbed normal paraffins are withdrawn from the adsorption zone ortower and either passed to storage for use, for example, as jet fuel or,if desired, subjected to further processing such as aromatization orhydroisomerization under well known or conventional conditions foradmixture with fresh hydroformate for passage through the molecularsieve treatment in order to recover further quantities of aromatics ornon-straight-chain paraflins.

EXAMPLE I A light virgin naphtha from West Texas crude boiling (5% to95%) in the range of 162 to 191 F. and having an API gravity of 67 .9and a research clear octane number of 66.3, was hydroformed bycontacting with a catalyst comprising 0.6 wt. percent platinum depositedon alcoholate alumina at a temperature of 900 F., a pressure of 50pounds per square inch, and in the presence of 2000 cubic feet of addedhydrogen per barrel of feed The feed rate was varied to changehydroforming severity. The hydroformate was then stabilized bydistillation to yield a C product which was vaporized and passed at 240F. over a 5 A. molecular sieve to adsorb normal paraflins. The 5 A.sieve is particularly well suited to the selective removal ofn-parafi'ms, the lowest octane components of the hydroformate. Figure 2shows a correlation of the vol. percent of n-parafiins removed as afunction of the hydroformate octane number.

Table I shows gasoline yield data obtained at diflFerent 1 levels ofhydroforming severity.

Table I.-Platinum hydroforming plus molecular sieve Hydrogen, 2,000O.f./b-

Process Period, Hrs 16 16 Research Octane No 66. 3 80.0 93.0

Octane Increase by Hydroforming 13. 7 26. 7

Yield of Hydroformate, Vol. Percent 100 85. 4 73.0

Sieve Treated Hydroformate:

1 Research Octane No 82.0 91. 2 100. 8

Yield, Vol. Percent on N aphtha Feed 76.0 68. 3 63. 1

Once-through Hydroforming Yield 0 r same Octane No 84. 0 75.0 58.0

' j i Without hydroforming; molecular sieve treat on naphtha teed.

As shown by the data obtained in Test #3, reforming product in betteryield than direct reforming to the This yield advantage is obtainedwithout recycle or any reforming treatment of the separated n-paraflins.However, correlations of gasoline yield as a function of octane level orreforming severity, Figure 3, show yield advantages for the combinedhydroforming-sieve treatment when producing gasolines above about 98octane number. To attain this octane level in the combination treatrequires an initial hydroformate of about 89-90, as shown in Figure 4.

At the 100 octane number level, further processing of the n-paraffinfraction by aromatization gives an additional 5 vol. percent yieldadvantage over direct platinum hydroforming alone,

In addition to the yield advantage, the combination operation allows theproduction of 100+ octane numbers with a reasonable cycle length in afixed-bed, 50 p.s.i.g. platinum operation and at a considerable increasein feed rate or plant capacity.

EXAMPLE II A straight run virgin naphtha from South Lousiana crudeboiling (5 to in the range of 225 F. to 306 F. and having an API gravityof 57.3 and a research clear octane number of 48.8 was hyd'roformed bycontacting with a catalyst comprising 10 wt percent M00 deposited uponactivated alumina containing about 2 wt. percent silica as a stabilizerat a temperature of 900 F., a pressure of 200 pounds per square inch andin the presence of 5000 cubic feet of hydrogen-rich recycle gas perbarrel of feed in a fluidized solids reactor system. The naphtha feedrate was varied from about 0.2 to 1.0 w./w./hr. at a catalyst to oilweight ratio of 0.9 to 1.0 to produce hydroformates of various octanenumber. The hydroformates were stabilized by distillation to yield a Cproduct which was vaporized and passed at 370400 F. over a 5 A.molecular sieve to adsorb normal parafrlns. The following tabulationshows a comparison of hydroformate yields at various octane levels bothwith and without molecular sieve treating.

Table II. Molybdenaalumina hlydr-oforming plus 1 Without hydroforming;molecular sieve treat on naphtha feed.

The results obtained with the heavy naphtha feed show a very definiteyield advantage for the combination process employing molecular sievesto remove unconverted normal paraifins when producing fuels above about102 research octane number. In addition to the yield advantages, thecombination process operates at greatly increased feed rates of 3 to 4times that required for the production of to 105 octane number fuels byhydroforming alone. The combination process also produces 5 to 10 vol.percent of high purity normal paraffins when operated at this octanelevel. In hydroforming without sieve separation, these paraflins areconverted to gas and coke.

The invention as described herein is a continuation-1'11- part of ourco-pending application Serial No. 588,105, filed on May 29, 1956, nowabandoned.

The foregoing description contains a limited number of embodiments. Itwill be understood that this invention is not limited thereto sincenumerous variations are possible without departing from the scope of thefollowing claims. 1

What is claimed is:

1. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about 110-375 P.which comprises contacting said fractions in admixture with ahydrogenrich gas with a hydroforrning catalyst at temperatures of800-975 F. and at pressures up to about 400 p.s.i.g., maintaining saidhydrocarbons in contact with the catalyst for a'period sufficient toproduce a C hydroformate having a Research Clear octane number of atleast 90, separating the hydroformate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal paraifins from the hydroformatevapors, and recovering hydroformate substantially free from normalparaffins.

2. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range \of from about 150225 F.which comprises contacting said fractions in admixture with ahydrogenrich gas with a catalyst consisting essentially of a platinumgroup metal dispersed upon alumina at temperatures of 800975 F. and atpressure between about 50 and 100 p.s.i,g., maintaining saidhydrocarbons in contact with the catalyst for a period sufficient toproduce a (3 hydroformate having a research clear octane number of atleast 90, separating the hydroformate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal parafiins from the hydroformatevapors, and recovering hydroformate substantially free from normalparaflins.

3. A method for producing 102+ research octane number rn'otor fuels fromhydrocarbon fractions boiling in the range of from about ZOO-350 F.which comprises contacting said fractions in admixture with ahydrogenrich gas with a hydrofoming catalyst at temperatures of 800975F. and at pressures of up to about 400 p.s.i.g., maintaining saidhydrocarbons in contact with the catalyst for a period sufficient toproduce a C hydroformate having a research clear octane number of atleast 95, separating the hydroformate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal paraflins from the hydroformatevapors, and recovering hydroformate substantially free from normalparafiins.

4. The process as defined in claim 3 in which the hydroforming catalystconsists essentially of platium upon alumina and the pressure is about300 p.s.i.g.

5. The process as defined in claim 3 in which the hydroforming catalystconsists essentially of molybdenum oxide upon alumina and the pressureis about 200 p.s.i.g.

6. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about 110 to 250 F.which comprises contacting said fractions in admixture with a hydrogen-;rich gas with a catalyst consisting of 0.01 to 1.0 wt. percent platinumupon an alcoholate alumina support at temperatures of 800 to 975 F. andat pressures below :about 125 p.s.i.g., maintaining said hydrocarbons incontact with the catalyst for a period sufiicient to produce ahydroformate having a research clear octane num- "ber of at least 90,separating the hydroformate from the the hydroformate, passing thehydroformate vapors through a bed of molecular sieves having porediameters of about 5 A. which selectively adsorbs normal paraffins fromthe hyduoformate vapors, and recovering hydroformate substantially freefrom normal paraffns.

7. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about 150 to 225 F.which comprises contacting said fractions in admixture with ahydrogenrich gas with a catalyst consisting of.'0.01 to 1.0 Wt. percentplatinum upon an alcoholate alumina support at temperatures of 800-975F. and at pressures between about 50 and p.s.i.g., maintainingsaidhydrocarbons in contact with the catalyst fora period sufiicient toproduce a C hydroformate having a research clear octane number of atleast 90, separating the hydroformate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing thehydroforrnate vapors through a bed of molecular sieves having porediameters of about 5 A. which selectively adsorbs normal p araflins fromthe hydroformate vapors, and recovering hydroformate substantially freefrom normal parafiins.

8. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about to 375 F. whichcomprises contacting said fractions in admixture with a hydrogen-richgas with a hydroforming catalyst at temperatures of 800-975 F. and "atpressures up to about 400 p.s.i.g., maintaining said hydrocarbons incontact with the catalyst for a period sufficient to produce a Chydroforrn ate having a research clear octane number of at least 90,separating the hydroformate from the accompanying normally gaseousmaterials, vaporizing the hydroformate, passing the hydroformate vaporsthrough a bed of molecular sieves having pore diameters of about 5 A.which selectively adsorbs normal paraflins from the hydroformate vapors,recovering hydroformate' substantially free from normal paraffins fromthe molecular sieve treatment, desorbing normal paraifins from themolecular sieves, subjecting the desorbed normal paraffins toisomerization and combining the isomerizate with the hydroformate.

9. A method fior producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about 110 to 375 F.which comprises contacting said fractions in admixture with ahydrogen-rich gas with a hydroforming catalyst at temperatures 800- 975F. and at pressures up to about 400 p.s.i.g., maintaining saidhydrocarbons in contact with the catalyst for a period lsufiicient toproduce a C hydroformate having a research clear octane number of atleast 90, separating the hydroforrnate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal parafiins from the hydroformatevapors, recovering hydroformate substantially free from normal paraflinsfrom the molecular sieve treatment, desorbing normal paraffins from themolecular sieves, subjecting the desorbed normal paraffins toaromatization and combining the aromatizate with the hydroformate.

10. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about l50-225 P.which comprises contacting said fractions in admixture with ahydrogenrich gas with a catalyst consisting essentially of a platinumgroup [metal dispersed upon alumina at temperatures of 800975 F. and atpressures between about 50 and 100 p.s.i.g., maintaining saidhydrocarbons in contact with the catalyst for a period suificient toproduce a C hydroformate having a research clear octane number of atleast 90, separating the hydroformate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing thehydro-formate v apors through a bed of moiecular sieves having porediameters of about 5 A. which selectively adsorbs normal parafiins fromthe hyldroform ate vapors, recovering hydrofonmate substantialiy tfireefrom normal paraffins from the molecular sieve treatment, desorbingnormal paraffins ilrom the molecular sieves, subjecting the desorbednormal paraffins to isomerization and combining the isomerizate with thenormal paratfin-free hydroformate.

11. A .rnethod for producing 102+ research octane number motor fuelsfrom hydrocarbon fractions boiling in the range of from about ZOO-350 F.which comprises contacting said fractions in admixture with ahydrogenrioh gas with a hydroforming catalyst at temperatures of SOD-975F. and at pressures of up to about 400 p.s.i. g., maintaining saidhydrocarbons in contact with the catalyst for a period suflicient toproduce a C hydroformate having a research clear octane number of atleast 95, separating the hydrofo-rmate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal paraifins uirom the hydroformatevapors, recovertig hydroformate substantially free from normal paraflinsfrom the molecular sieve treatment, desorbing normal parafiins from themolecular sieves, subjecting the desorbed normal paraflins to isomerization and combining the isomerizate With the normal parafiin-freehydroformate.

12. A method for producing 102+ research octane number motor fuels dromhydrocarbon iractions boiling in the range of irom about ZOO-350 F.which comprises contacting said iractions in admixture with ahydrogenrich gas with a hydrofiormziug catalyst at temperatures or800975 F. and at pressures of up to about 400 p.s.i.g., maintaining saidhydrocarbons in contact with the catalyst for a period suflicient toproduce a C hydrofo-rmate having a research clear octane number of atleast 95, separating the hydrosform-ate from the accompanying normallygaseou materials, vaporizing the hydroforrnate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal paraffins from the hydroformatevapors, recovering hydroformate substantially free from normal paraffinsfrom the molecular sieve treatment, desorbing normal paraflins from themolecular sieves, subjecting the desorbed normal paraffins toaromization and combining the aromatizate with the normal paraflin-freehydroformate.

13. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about 110 to 250 P.which comprises contacting said iractions in admixture with ahydrogen-rich gas with a catalyst consisting of 0.01 to 1.0

wt. percent platinum upon an alcoholate alumina support at temperaturesof 800 to 975 F. and at pressures below about 125 p.s.i.g., maintainingsaid hydrocarbons in contact with the catalyst for a period suflioientto produce a C hydroiomnate having a research clear octane number of atleast 90, separating the hydro formate from the accompanying normallygaseous materials vaporizing the hydroformate, passing the hydroformatevapors through a bed of molecular sieves having pore diameters of about5 A. which selectively adsorbs normal parafiins from the hydroiformatevapors, recovering hydroformate substantially free from. normalparaffins from the molecular sieve treatment, desorbing normal parafiinsfrom the molecular sieves, subjecting the desorbed normal paraflins toisomerization and combining the isomerizate with the hydrotformate.

14. A method for producing 100+ research octane number products fromhydrocarbon fractions boiling in the range of from about 150 to 225 P.which comprises contacting said fractions in admixture with ahydrogen-rich gas with a catalyst consisting of 0.01 to 1.0 wt. percentplatinum upon an alcoholate alumina support at temperatures of SOD-975F. and at pressures between about and p.s.i.g., maintaining saidhydrocarbons in contact with the catalyst for a period sufiicient toproduce a C hydroformate having a research clear octane number of atleast 90, separating the hydroformate from the accompanying normallygaseous materials, vaporizing the hydroformate, passing the hydroformate vapors through a bed of molecular sieves having porediameters of about 5 A. which selectively adsorbs normal paraffins fromthe hydroformate vapors, recovering hydroformate substantially free fromnormal paraffins from the molecular sieve treatment, desorbing normalparafiins from the molecular sieves, subjecting the desorbed normalparaflins to isomerization and combining the isomerizate with thehydroformate.

References Cited in the file of this patent UNITED STATES PATENTS2,740,751 Haensel Apr. 3, 1956 2,818,449 Christensen et al Dec. 31, 19572,818,455 Ballard et a1. Dec. 31, 1957

1. A METHOD FOR PRODUCING 100+ RESEARCH OCTANE NUMBER PRODUCTS FROMHYDROCARBON FRACTIONS BOILING IN THE RANGE OF FROM ABOUT 110-375*F.WHICH COMPRISES CONTACTING SAID FRACTIONS I N ADMIXTURE WITH A HYDROGENRICH GAS WITH A HYDROFORMING CATALYST AT TEMPERATURES OF 800-975*F. ANDAT PRESSURE UP TO ABOUT 400 P.S.I.G., MAINTAINING SAID HYDROCARBONS INCONTCT WITH THE CATALYST FOR A PERIOD SUFFICIENT TO PRODUCE A C5+HYDROGORMATE HAVING A RESEARCH CLEAR OCTANE NUMBER OF AT LEAST 90SEPARATING THE HYDROFORMATE FROM THE ACCOMPANYING NORMALLY GASEOUSMATERIAL, VAPORIZING THE HYDROFORMATE, PASSING THE HYDROFORMATE VAPORSTHROUGH A BED OF MOLECULAR SIEVES HAVING PORE DIAMETERS OF ABOUT 5 A.WHICH SELECTIVELY ADSORBS NORMAL PARAFFINS FROM THE HYDROFORMATE VAPORS,AND RECOVERING HYDROFORMATE SUBSTANTIALLY FREE FROM NORMAL PARAFFINS.